By Svea Herbst-Bayliss

May 6 (Reuters) - Hedge fund Marcato Capital Management said on Monday it opposed marijuana company Acreage Holdings Inc's $3.4 billion sale to rival Canopy Growth Corp , arguing Acreage was too hasty in agreeing to a deal at too low a price.

Marcato, which owns 2.7 percent of Acreage, wrote to the company's board of directors to argue that the proposed takeover, which was agreed to last month and will be voted on by shareholders next month, is "lopsided in Canopy's favor."

"It is highly imprudent for Acreage to sell itself today at the proposed valuation, with so much unlocked growth and value embedded in the Company," Marcato portfolio manager Mick McGuire wrote in the letter seen by Reuters.

In April, Smiths Falls, Ontario-based Canopy said it would pay $3.4 billion in cash and stock for New York-headquartered Acreage, giving Acreage investors $300 million in cash upfront. Acreage shareholders will also receive Canopy shares at a later date, when marijuana use is legalized at a federal level in the United States.

While medical and recreational marijuana use is permitted in many U.S. states, it is still prohibited by federal law, and the deal could be called off if marijuana use does not become legal across the country in the next 7-1/2 years.

Since the announcement, Canopy's stock price has jumped 15 percent while Acreage's shares have dropped 6 percent. On Friday, Acreage's stock closed at $22 a share, below the $25 per share price of its initial public offering last November, and far below sell side analysts' stock price targets of $31 to $42 a share.

"Canopy's market capitalization has increased by roughly $3.5 billion since the deal announcement, indicating pro forma economic value to Canopy of $6.9 billion -- over 100 percent greater than the price offered to Acreage shareholders," the letter said.

Marcato is speaking up about the planned takeover days before the May 13 record date when shareholders become eligible to cast their vote and will spearhead opposition when they vote on June 19.

McGuire urged Acreage's board, which is stocked with well-connected former politicians including former Canadian prime minister Brian Mulroney and John Boehner, a former speaker of the U.S. House of Representatives, to wait.

"Remain independent" and "run a formal and competitive sale process", the letter said, noting that once the regulatory landscape in the cannabis sector clears, other bidders including tobacco and spirits companies could make offers. (Reporting by Svea Herbst-Bayliss in Boston; Editing by Daniel Wallis)